In utility vehicles, typically manual-shift transmissions or even automated manual-shift transmissions are used as group transmissions. Such manual-shift transmissions and automated manual-shift transmissions are highly efficient and relatively inexpensive. In such manual-shift transmissions and automated manual-shift transmissions gearshifts take place with traction force interruption.
The use of dual-clutch transmissions in passenger cars is increasing. In such dual-clutch transmissions, gearshifts can be carried out without traction force interruption. However, dual-clutch transmissions are relatively large and heavy, and incur higher purchase costs. Moreover, dual-clutch transmissions can only be used as group transmissions to a limited extent, since due to the fact that with group transmissions an almost geometrical gear gradation is desirable, when a dual-clutch transmission is used the gear intervals are too small in the lower gears and accordingly too large a number of shifts would be necessary in the lower gears. This is also because with a dual-clutch transmission, by virtue of the system individual gears cannot be skipped.
From DE 10 2011 087 947 A1 a group transmission comprising a main transmission and a range transmission downstream therefrom is known, wherein the main transmission comprises two planetary gearsets or planetary gear assemblies and four interlocking shifting elements and the range transmission also comprises two planetary gearsets or planetary gear assemblies and four interlocking shifting elements.
There is a need for a group transmission for a motor vehicle, which while having a compact structure, a large ratio spread and high efficiency, can provide a large number of gears with approximately geometrical gear gradation.